The Boston system was developed by the British firm Masabi. Massachusetts Bay Transportation Authority officials said they expected to save millions a year in the cost of making onboard transactions, which slow conductors on crowded trains.

Boston appears to have addressed some of the biggest problems that Metra faces with its ticketing, officials said.

Since Metra fares are distance-based —- meaning the farther riders live from downtown Chicago, the higher the fares — conductors must be able to readily identify various tickets. Metra riders also use different types of tickets: one-way, 10-ride and monthly passes.

A smartphone app can be used to buy and display different tickets, based on the customer's preference, said Jeff Brantz, Metra's manager of schedules and service.

Customers could use their credit cards to buy tickets as needed or put money in a "virtual wallet," he said.

The phone tickets could also indicate that users are senior citizens or students and eligible for reduced fares. Such riders would need to verify their status by showing identification.

The app used in Boston also displays service alerts, delays, and the routes and train schedules for the entire Massachusetts Bay area. That information can be updated constantly.

"It's a pretty handy tool for you to have in your pocket," Brantz said.

Another hurdle that could be solved is to make Metra's ticketing system compatible with the CTA's and Pace's. Commuters who use the CTA's Ventra would be able to use its credit card feature to buy Metra tickets with the app.

Ciavarella said the app would satisfy a state law requiring Metra to be part of a regional fare payment system by Jan. 1. The law is aimed at enabling customers to use contactless credit cards, debit cards and prepaid cards to pay for public transportation.

Metra had long balked at updating its technology. The rail line only started accepting credit cards for purchases in 2010.

The app would probably not eliminate paper tickets entirely, officials said, because not everyone has a smartphone.

The Chicago Cubs on Tuesday sought City Hall permission to expand construction hours at Wrigley Field, with bleacher work falling well behind schedule on the team's $375 million ballpark renovation project.